Positive Tension - Riggers

[geanky 0]

How do you feel about using positive tension devices when closing containers? And how do you feel about manufactures that explicitly say that you shouldn't use these when closing their containers (e.g. Rigging Innovations)?

learn to fly in 3d

[miller 0]

I personally use a positive tension device to close most reserves (MOST). However, when I was learning to become a rigger I never used one, so I can respect just how much tension can be produced with one of these little gizmos. I definitely think they can be used safely. The maximum pull force allowed for a reserve ripcord is 22lbs (see the Poynter's manual for the exact test). I personally think (from experience) that if you can close a rig, either by pulling or by using a positive tension device and you're exceeding the 22lb limit without damaging the loop or the pull-up cord, something is wrong.

Also, if you measure pull force right after closing a rig verses waiting a day or two, the pull force almost always decreases with time. Things stretch, fabric moves around a little, etc. Have you ever gotten your rig back from getting repacked and it looks all nice, and then a month or two into the repack cycle you start to see the ring of your pilot chute top through all of the flaps, or in the case of a javelin the pop top starts to rock a little?

Anyway, as a rigger it's my job to follow manufacturer's instructions, so if RI says not to use one, I won't use one. Why do they recommend this? Probably a lot of reasons, but it's their right, their system.

[slotperfect 7]

I don't pack a lot of RI rigs, but if the packing instructions specifically forbid it, I would substitute my wooden dowel and a closing plate.

Otherwise I always use one. After I have removed the pull-up cord, I work the pin with my fingers. My rule of thumb (sorry for the pun) is if I can move it with my fingers, it's well within the 22lb limit. If it seems tight I do a pull-test. I have a friend put the rig on, I remove the ripcord from the pocket, and pull straight down with my little scale. I have a little gizmo I got from Dave DeWolf that keeps the pin from coming out of the loop.

Most rigs have CYPRES's these days, and the silicone-impregnated spectra closing loops allow for a tighter pack job because they cause much less friction than Ty IIA sheathing.

When in doubt, do a pull-test!

Arrive Safely

John

[fasterfaller 0]

I quit using those years ago . They CAN do damage to grommets and to stiffners . I have seen damage done to cypres cartridges and when tested they did not fire . I have found that the more I rig , the less tools I need .

[alan 1]

If you are pulling the handle straight down, I don't think you are doing the test correctly.

alan

[slotperfect 7]

Please elaborate

Arrive Safely

John

[polarbear 1]

I've never used a positive tension device (the so-called "donkey dick"). I use my packing paddle and closing plate, which I suppose is a form of positve leverage device.

I also check to see that I can move the pin with my fingers...that is my rule of thumb.

"Holy s*** that was f***in' cold!"

[riggerrob 643]

Positive leverage devices were banned in Canada long before I became a rigger 16 years ago, so I have never owned one.
Ergo I have only used PLDs to pack a handful of ejection seat rigs.
When an arm injury limited my grip strength 9 years ago, I developed a new tool that does the same job, leaves both hands free and gives me clear feedback on how much tension I am applying.
My "packing hook" is the essence of simplicity. It consists of an old B-12 snap and a molar strap. I remove the gate from the B-12 snap and slip it on to the molar strap. Then I wrap the molar strap diagonally around my shoulders, so the snap hangs in the middle of my chest and tie the pull up cord to the snap with a series of half-hitches or lark's head knots. This leaves both hands free for temp pins, steering flaps, compressing pilot chutes, etc.

[rabio 0]

Quote

If you are pulling the handle straight down, I don't think you are doing the test correctly.

The handle should be pulled straight down in the same direction as the reserve housing. Pulling it in any other direction can and will damage the brass cap on the end of the housing.

[polarbear 1]

Quote

The handle should be pulled straight down in the same direction as the reserve housing. Pulling it in any other direction can and will damage the brass cap on the end of the housing.

But it will also probably increase the pull force. The test specifies that the MAXIMUM pull force be 22 lbs - this is in the direction that gives the highest pull force, which is not straight down.

In addition, in actual use, a real ripcord will probably not be pulled straight down, but out to the side.

"Holy s*** that was f***in' cold!"

[rabio 0]

Pointers manual does not mention maximum pull force. The requirements are "the force required to open the container should no exceed 22 lbs" The direction of the pull falls under standard operating procedures found in any cotainer manufacturers manual and is not mentioned in that section of the pointers manual. The USPA S.I.M allso states that all handles should be pulled straight down in the same direction of the housing.
When checking a product it should be done in accordance with the manufacturers specifications and standard operating procedures. If you pull against the direction of the housing you will damage it and the cost of replacing the housings is about $20.00.

[alan 1]

AS 8015A issued by the Society of Automotive Engineers details the minimum performance standards for parachute assemblies and components for emergency use. PPM Vol II contains the text. I think the relevant part is on page 39, 4.3.2.2 Pull Test: A load AT THE RIPCHORD HANDLE of not less than 5 lbf (applied in the direction giving the lowest pull load) nor more than 22 lbf [APPLIED IN THE DIRECTION GIVING THE HIGHEST PULL LOAD UNDER NORMAL DESIGN OPERATIONS] shall be required to cause a positive and quick functioning of the parachute assembly on all tests. ......

As 8015A is the standard for TSO testing, but I believe the same standard applies to any reserve we repack IAW the FARs. I had hoped that my response would have motivated a few people to look this up because we seem to always focus on the 22 lbf force to pull the reserve pin and forget that there is also a minimum pull force that is just as important. We also forget that the 22 lbf load is not necessarily in the direction that gives the lowest load. Most reserve handles are pulled somewhere in between straight away from the body and straight down. The key words are "under normal design operations" I hope this has helped clarify my comment and has illuminated some faded information.

alan

[alan 1]

You may want to check my reply to Slotperfect. PPM Vol II does mention both max and min pull forces as detailed in AS 8015A. It can be found on page 39. These are the standards for TSO testing and I believe apply to the reserves we repack IAW the FARs. I have just reviewed the manufacturers manuals for the Mirage, Javelin and Talon and none of those have any standard operating procedures in them that specifies pulling the handle in the same direction as the housing or straight down. I don't have time to review all of the manuals, but I would guess that if that instruction exists in any of them, it is the exception rather than the norm. I agree that any procedure done on a container should be done IAW the mfgr's instructions.....where they exist. When in doubt, call them. They all are tested in compliance with AS 8015A though, so I would hardly expect that to be in conflict. Yes, if you repeated the test over and over, it would damage the housing, that is why we usually only do the test when there is some doubt that the max and/or the min pull forces would not be met. The SIM??? Well, that is just a recommendation from USPA on what they believe will be the safest method of deploying the reserve. It makes sense too, but it takes a back seat to the FARs, AS 8015A, the mfgr's instructions and even PPM. As a side note, I know that the RSL, when it pulls the reserve cable, does it in some direction other than in line with the housing. By design. It is hard on the cable and the housing, but seldom do either need replacing, even after several activations. Well, so much for my 2 cents.

alan

[councilman24 37]

You should respect the manufacturer's instructions. The last packing demo I saw for Sunpath Javelin at the 2001 PIA symposium, they (don't remember who did the demo) that you can't pack one correctly without using something. A kneeling plate spans the PC and doesn't allow it to be set deep enough. For us old and moldy guys the best thing I ever bought was ratcheting closing aid. Uses a socket wrench, axle, cog, and u shaped support. Their not cheap (a few hundred dollars) but a well know rigger sells them to the military. I'm not saying who it is because I'm not sure he want's to sell them to the general public. But I can rip a rig apart if I don't us it carefully. I also liked the idea of the shoulder strap and b-12 snap. I've seen that used. (Of couse these days most people would have to BUY a B-12 snap to make one!)

Hey, what's Dave device for keeping the pin in look like? I don't remember that one.

Terry

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[slotperfect 7]

Quote

Hey, what's Dave device for keeping the pin in look like? I don't remember that one.

I'll see if I can get a pic posted next week

Arrive Safely

John